Chemistry 12 week
Ion-dipole
between ion and polar molecule; increases with magnitude of dipole moment, magnitude of ionic charge and decreasing separation
Bond order
# bonds= 1/2(#electrons in bonding MO-# of electrons in antibonding MOs)
Which of the compounds listed below are capable of forming hydrogen bonds between their molecules?
(CH3)2NH, HF, HOCH2CH2OH
lowest to highest change in energy
(lowest)Metal, semiconductor, insulator(higher)
intrinsic semiconductor
conducts electricity, but not as well as a typical metal
gas to solid
deposition
Potential
energy by virtue of its position relative to a force Ex. Gravity
Endothermic
energy enters system Absorbs heat Ex. Bond breaking melting sublimation
Exothermic
energy leaves system Releases heat Ex. Bond making Wax hardening Dew Formation Na+ + Cl- ---->NaCl
Kinetic
energy of motion
Surface Tension
energy you have to put in to deform the surface of a liquid
Hydrogen bonds
especially strong type of dipole-dipole; occurs between molecules with H and N,O,F
liquid to solid
freezing
energy flows from
high temp to low temp
Anti bonding Molecular orbitals
higher energy, so less stable tan separated atoms
entropy
how much you spread energy out
electrolyte
is a solute that has mobile ions carry current
solution
is homogeneous mixture ex. air, salt water
"p" and "n" indicate
junction
IMF=KE
liquid
Bonding Molecular orbitals
lower energy; so more stable than separated atoms
work
manifestation of energy transfer due to a mechanical process directed energy (directed energy) w= F x D
heat (q)
manifestation of energy transfer due to a temperature differnce non-directed, random energy
solid to liquid
melting
molarity
moles of solute/liters of solution
n-type
negative particle (electron)
Dipole-dipole forces
occur between polar molecules; increases with strength of dipole
London Dispersion forces
occurs between all molecules; depends on mass, size and polarity
System
part of the universe that you are interested in
p-type
positive charge carrier
state function
property of a system just by virtue of position wherever its in
path function
property of a system which depends on how you do it
thermal equilibrium
situation that results spontaneously sometime after two objects at different temperatures are brought into contact
IMF>KE
solid
ionic compounds (metal + nonmetal)
strong electrolyte
Arrange the ionic compounds CaO, BaCl2, and Na2O in order of decreasing strength of the attraction between their ions.
strong-CaO,Na2O,BaCl2-weak
Thermodynamics
study of energy and its transformations
solid to gas
sublimation
Acids
tart taste turn blue paper red
Viscosity
the ability of molecules to flow -Viscosity decreases, IMF decreases
Energy
the capacity to do work
Which of the following best describes the term molar heat of vaporization?
the heat required to convert 1 mole of a liquid substance at its boiling point to the vapor state
Which of the following best describes the term molar heat of fusion?
the heat required to convert 1 mole of a solid substance at its melting point into the liquid state
Surroundings
the rest of everything else in the universe
Universe
the sum of system and surroundings
boiling point
the temperature at which a liquid and gas phase are in equilibrium
Bases
turn paper blue slippery
most molecular covalent compounds are
weak or electrolytes Ex. Sucrose, Ethanol
energy transfer continues until
you reach thermal equilibrium
CH3CH2CH3 lewis structure
-Polarity:Nonpolar -London: Yes -Dipole-Dipole:No -Hydrogren Bonds: No
CH3COCH3 (Acetone)
-Polarity:Polar -London: Yes -Dipole-Dipole:Yes -Hydrogen Bonds: No
CH3CHOHCH3 lewis structure
-Polarity:Polar -London: Yes -Dipole-Dipole:Yes -Hydrogen Bonds: Yes
Glycerol
-Polarity:Polar -London: Yes -Dipole-Dipole:Yes -Hydrogen Bonds: Yes
Propanoic acid
-Polarity:Polar -London: Yes -Dipole-Dipole:Yes -Hydrogen Bonds: Yes
Cost energy
-breaking up solvent-solvent interactions -breaking up solute-solute interactions
Which of the following phase transitions are exothermic?
-freezing -deposition -condensation
Which of the following phase transitions are endothermic?
-melting -evaporation -sublimation
CH3COOH (acetic acid) can form hydrogen bonds between its molecules. Based on the Lewis structure shown below, how many hydrogen bond donor and acceptor atoms does this molecule have?
1 H-bond donor atom; 4 H-bond acceptor sites
When an object is heated, the quantity of energy transferred depends on
1)substance 2)Mass of Substance 3)change in temp
extrinsic semiconductor
A doped semiconductor
first law of thermodynamics (law of conservation of energy)
DeltaEuniv = DeltaEsys + DeltaEsurr= 0
Why do the strengths of London (dispersion) forces generally increase with increasing molecular size?
Dispersion forces arise from dipoles caused by the electron distribution being distorted. Larger molecules have more electrons and, therefore, more distortions and a bigger force.
IMF<<KE
GAs
Strong Acids
HCl HBr HI HNO3 HCLO4 H2SO4
If the reaction is endothermic, what happens to the internal energy of the system when the reaction is proceeding?
It increases.
most common strong bases
Metal OH
Dilutions
Molarity1 x Volume1 = Molarity2 x Volume2
Which, if any, of the following nitrogen oxides have the same empirical formula?
N2O4, NO2
most common weak base
NH3
Which of the following compounds could form a hydrogen bond with another molecule of the same compound?
NH3, Ch3OH
What causes the high viscosity of molasses?
The intermolecular forces between the molecules of molasses (hydrogen, dipole-dipole and dispersion) are substantial because the molecules are large and the interactions between the molecules are strong.
Equlibirum
a dynamic condition described by equal rates for opposite processes
Titrations
acid + base ---> water + salt
soluble ionic compounds and acids are
all electrolytes
specific heat
amount of heat energy you have to add to a substance to change its temp of 1 gram ofmaterial by 1 degree -Units: J/g degree Celsius
Hydrogen bonding is an attractive force that plays a key role in determining the physical properties of molecular substances. What features are required for a substance to experience hydrogen bonding among its own molecules?
an O, N, or F atom with one or more lone pairs H bonded covalently to O, N, or F
Weak Acid
any other acid
Why are hydrogen bonds considered a special class of dipole-dipole interactions?
These interactions are with polar molecules but are stronger than dipole-dipole interactions. These interactions account for the higher melting and boiling points observed for certain molecules such as water.
System + Surroundings=
Universe